CODEWITHSUNDEEP
bash
Jelle De Loecker
Jelle De Loecker

Reputation: 21915

Concatenating strings in bash overwrites them

I'm parsing query results from a mysql command (with the --table parameter)

local records=`echo "${query}" | $MYSQL -u $MyUSER -h $MyHOST -p$MyPASS --table`

The query is run successfully, and I receive good data.

Then I iterate over this data:

for data in $records ;
do
    test+=$data
done

The code is more extensive, but this is basically it. Bash sees every space as a separator though, and that's a problem for text fields.

So I just concatenate them. But when I feed bash this data:

*URL*
host:
test.url.com
pass:
anothertest

http://www.test.com

It concatenates it to something like:

pass:test.url.com.com

As if it's not concatenating, but overwriting. Is this maybe some carriage return problem?

Upvotes: 12

Views: 11414

Answers (4)

cweigel
cweigel

Reputation: 1553

I had the same issue with the stderr output retrieved from the curl command. I found that the output contains carriage return that needs to be removed. For the example above this could be done using the tr tool:

for data in $records ;
do
    data=$(echo "$data" | tr -d '\r')
    test+="$data"
done

Upvotes: 37

fdermishin
fdermishin

Reputation: 3686

Check that you use Unix line endings. Using Windows line endings caused the same behavior for me, overwriting strings.

Upvotes: 9

Stephen Connolly
Stephen Connolly

Reputation: 14096

Have a look at setting the IFS variable if you are seeing issues with line separators.

Something like

IFS="\n"

Also be careful with += as it can fall back to array manipulation depending on the version of BASH.

Upvotes: 0

a.drew.b
a.drew.b

Reputation: 84

Make sure you're using Bash 3 or later. The += operator in Bash can be used to manipulate an Array. It will use the current value of the IFS variable to split the tokens and add the value to the array.

Try: test="$test $data" to concatenate the data

Upvotes: 2

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